Wednesday, December 12, 2007

Solar heating and hot air

A recent paper in Journal of Geophysical Research (N. Scafetta and B. J. West, Vol. 112, D24S03, 2007, full text here) says that over 50% of global warming since 1900 may have been caused not by CO2 but by the Sun:

We compare different preindustrial temperature and solar data reconstruction scenarios since 1610. We argue that a realistic climate scenario is the one described by a large preindustrial secular variability (as the one shown by the paleoclimate temperature reconstruction by Moberg et al. (2005)) with the total solar irradiance experiencing low secular variability (as the one shown by Wang et al. (2005)). Under this scenario the Sun might have contributed up to approximately 50% (or more if ACRIM total solar irradiance satellite composite (Willson and Mordvinov, 2003) is implemented) of the observed global warming since 1900.

Separately, another paper to be published in Journal of Geophysical Research - Atmospheres (R. R. McKitrick and P. J. Michaels, full text here) examines the post-1980 temperature data. They find that half of the reported temperature rise is due to experimental measurement error.

If further research confirms that half the recent temperature rise is due to the Sun (as per Scafetta and West) and half is due to measurement error (as per McKitrick and Michaels), then at least Al Gore need have no guilt about continuing to fly by private jet.